1. Field of the Invention
The present invention relates to screen formation systems, screen formation methods, and programs.
2. Description of the Related Art
In conventional navigation devices, when a driver as an operator inputs a destination and sets search conditions, route search processing is performed based on the search conditions, and a route from a departure point represented by a current position to the destination is searched based on map data. Then, the searched route, i.e., a search route is displayed together with a vehicle position indicating the current position of a vehicle on a map screen formed in a display unit, and search route guidance, i.e., route guidance is performed. In addition to the display of the search route on the map screen, route guidance by voice is also performed.
Consequently, the driver can drive the vehicle along the displayed search route.
In the navigation devices, in order to improve the response of the display unit, an off-screen is drawn while a predetermined screen is formed as a current screen in the display unit so that the time of changing a screen can be reduced. When a vehicle approaches a first intersection, the screen formed in the display unit changes from a map screen to an enlarged view of the first intersection. If it is expected that the enlarged view of a second intersection will be formed, the enlarged view of the second intersection is drawn as an off-screen in advance. Then, after the vehicle passes the first intersection, the screen formed in the display unit changes from the enlarged view of the first intersection to the enlarged view of the second intersection (refer to Japanese Patent Application; Publication No. JP-A-6-66574, for example).